Innovative concepts for hybrid multi-level converters for HVDC power transmission

2010 ◽  
Author(s):  
C.C. Davidson ◽  
D.R. Trainer
Keyword(s):  
Power Transmission ◽  
Multi Level

Study on Post-Evaluation for the Power Transmission and Transformation Project Based on AHP-Fuzzy Comprehensive

2013 ◽  
Vol 756-759 ◽  
pp. 2668-2672 ◽  
Author(s):  
Jian Xun Qi ◽  
Shu Liang Liu ◽  
Zhao Ying Sun
Keyword(s):  
Evaluation Method ◽  
Power Transmission ◽  
Comprehensive Evaluation ◽  
Evaluation Model ◽  
Fuzzy Comprehensive Evaluation ◽  
Economic Benefits ◽  
Comprehensive Evaluation Method ◽  
Post Evaluation ◽  
Multi Level ◽  
Project Sustainability

On the basis of the basic theory of post evaluation of power transmission and transformation project in this paper, it selects the multi-level fuzzy comprehensive evaluation method to evaluate the project. Take the Qian Fangzi power transmission and transformation project as an example;It has carried on the empirical research. From the process of the project implementation, economic benefits, the influence of the project, sustainability evaluation and so on, it has achieved good results and proved the effectiveness of the proposed evaluation model.

scholarly journals SIMULATION OF COMMUTATION PROCESSES OF MULTI-LEVEL VOLTAGE INVERTER SWITCHES

2021 ◽  
pp. 83-93
Author(s):  
Ekaterina E. Mirgorodskaya ◽  
Vadim A. Kolchev ◽  
Mikhail E. Mamonychev ◽  
Nikita P. Mityashin ◽  
Anastasia S. Shcherbakova
Keyword(s):  
Reactive Power ◽  
Power Transmission ◽  
Input Current ◽  
Output Curve ◽  
Inductive Load ◽  
Power Circuit ◽  
Voltage Inverter ◽  
Emergency Situations ◽  
Pulsed Dc ◽  
Multi Level

An algorithm for controlling of commutator’s transistors of a single-phase multi-level voltage inverter is presented. The structure of the power circuit of the considered converter, in contrast to most existing circuits, does not depend on the levels number of the output curve due to the using of an universal source of levels, which are formed by output capacitors of two pulsed DC-converters. The commutator control algorithm ensures the formation of the required output curve of the inverter and excludes the occurrence of emergency situations during level commutating. Features of the converter and commutator operation in modes of active power transmission from pulse converters to the load and perception of the reactive power of the inverter load by them are considered. The commutator operation algorithm determines the sequence of control pulses, applied to the base of transistors, the sequence being synchronized with the process of the output voltage curve forming, as well as the direction of the inverter input current. At the same time, features of the level commutating are considered. They differ in the transition direction in value of level voltages: «up» from a lower value to a higher one and «down» from a higher value to a lower one. The sequence of supply and removal of pulses from control electrodes of switches and commutations caused by them, when the inverter input current is positive, are given. The similar commutating of levels is realized, when the inverter input current is negative. Wherein indexes of switches are rearranged in accordance with the direction replacement of their switching of the commutator circuit. A commutator model is realized using Micro-Cap 12 to demonstrate the operation of the algorithm. The transistor MJ15003 model is used as a commutator’s switch. In the model, output capacitors of pulse converters are represented by voltage sources, an autonomous inverter – by an active inductive load. The commutating from a higher voltage level to a lower one with a positive input current of the inverter is considered as an example. Simulation results confirm the performance of the algorithm.

Research on Direct Power Control of Modular Multi-level Converter for Power Transmission

2012 ◽  
Vol 40 (15) ◽  
pp. 1731-1749 ◽  
Author(s):  
Jie Wu ◽  
Zhi-Xin Wang ◽  
Guo-Qiang Wang ◽  
Shuang Li ◽  
Ding-Guo Wu
Keyword(s):  
Power Control ◽  
Power Transmission ◽  
Direct Power ◽  
Direct Power Control ◽  
Multi Level ◽  
Level Converter

scholarly journals Dynamic Performance Analysis of VSC-HVDC Based Modular Multilevel Converter under Fault

2021 ◽  
Vol 54 (1) ◽  
pp. 187-194
Author(s):  
Abdelhalim Yahiaoui ◽  
Koussaila Iffouzar ◽  
Kaci Ghedamsi ◽  
Kamal Himour
Keyword(s):  
Power Transmission ◽  
Dynamic Performance ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
System Control ◽  
Hvdc System ◽  
Power Transmission Systems ◽  
Multi Level ◽  
Level Converter ◽  
Dynamic Performance Analysis

The use of high voltage direct current based voltage source converter (VSC-HVDC) in power transmission systems knows a great progress in recent years. Above all, with the new generation of power electronics converters such as the modular multi-level converter (MMC), with his scalable structure it can theoretically meet any voltage level requirement, which allows to increase the size of the power transferred compared to conventional converters. In this sense, this paper presents a study of a VSC-HVDC system based on a modular multi-level converter (MMC). The main objective of this work is to analyze the performance of the VSC-HVDC system based MMC without the AC filters and its control in the event of a fault, during set point changes and unbalanced grid conditions. After realization a mathematical model of the system studied and its control, simulations are done over in Simpower System/Matlab. The results obtained confirm the robustness of the system control and the system gives a good energy quality, that manifests by a good output currant and voltage curves with no need to use a voluminous AC filter.

Verlaufsanalyse wöchentlicher Selbst- und Fremdeinschätzungen in der Langzeittherapie suchtkranker Jugendlicher

2019 ◽  
Vol 47 (2) ◽  
pp. 126-137
Author(s):  
Ferdinand Keller ◽  
Tatjana Stadnitski ◽  
Jakob Nützel ◽  
Renate Schepker
Keyword(s):  
Allen Vier ◽  
Multi Level

Zusammenfassung. Fragestellung: Über Veränderungen in der emotionalen Befindlichkeit von Jugendlichen während einer Suchttherapie ist wenig bekannt. Methode: Die Jugendlichen füllten wöchentlich einen entsprechenden Fragebogen aus, analog ihre Bezugsbetreuer eine parallelisierte Kurzfassung. Von 42 Jugendlichen liegen insgesamt 853 Bogen und von den Bezugsbetreuern 708 Bogen vor. Die Fragebogen wurden zunächst faktorenanalytisch hinsichtlich ihrer Dimensionalität ausgewertet, anschließend wurden gruppenbezogene Verlaufsanalysen (Multi-Level-Modelle) und Abhängigkeitsanalysen auf Einzelfallebene (Zeitreihenanalysen) durchgeführt. Ergebnisse: Im Jugendlichenfragebogen ergaben sich vier Faktoren: negative Befindlichkeit, Wertschätzung von Therapie/Betreuung, Motivation und Suchtdynamik. Die Übereinstimmung zwischen den Jugendlichen- und der (einfaktoriellen) Betreuereinschätzung fiel insgesamt niedrig bis mäßig aus, brachte aber auf Einzelfallebene differenziertere Ergebnisse. Im Verlauf nahmen die Werte auf allen vier Jugendlichenskalen ab. Einzig der Verlauf der Wertschätzung in der Eingewöhnungsphase war prädiktiv für den späteren Abbruch der Maßnahme: Bei den Abbrechern nahm die Wertschätzung ab, während sie bei den Beendern initial stieg. Schlussfolgerungen: Der bedeutsamste Faktor in Bezug auf die Therapiebeendigung suchtkranker Jugendlicher scheint die Wertschätzung von Therapie/Betreuung zu sein, während die Motivation jugendtypische Schwankungen aufweist. Der Suchtdynamik kam eine deutlich weniger bedeutende Rolle zu als allgemein angenommen. Programme in der Langzeittherapie sollten die Wertschätzung von Therapie/Betreuung künftig mehr fokussieren als die Suchtdynamik.

A Multi-level Measure Of Safety Climate And Associations With Safety Behaviors In The Fire Service

2017 ◽  
Author(s):  
Todd D. Smith ◽  
Mari-Amanda Dyal ◽  
Yongjia Pu ◽  
Stephanie Dickinson ◽  
David M. DeJoy
Keyword(s):  
Safety Climate ◽  
Fire Service ◽  
Safety Behaviors ◽  
Multi Level
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